One of the spacecraft orbiting Mars has snapped some pictures of what could be the entrances to huge caves. You may be looking at the future site of our first Mars colony.
These big black pits were first spotted a year ago, but last month, the HiRISE camera on the Mars Reconnaissance Orbiter was able to take some high resolution images of the site. By overexposing the surface, the camera was able to see down into the pits. To give you a sense of scale, the smallest objects you can see in these images are about three feet across, and the pit in this image is about the size of a football field:
Researchers think that these are probably pit craters, which form when the ceiling of an empty lava chamber collapses. They may not necessarily be part of a lava tube or cave system, and it's hard to tell for sure from the pictures. But even if there isn't a cave system there, there are some good reasons to live underground on Mars, especially if you're going to be there for a while. In addition to making it easier to regulate temperature, being surrounded by a whole bunch of rock helps to keep radiation to a minimum.
One possible way to turn a pit crater into an insta-base might be to stretch a big sheet of plastic wrap over the top at ground level to seal it off, and then fill the inside with air. The air pressure inside would help hold the plastic roof up, and you'd end up with a big sunny open area, which could be good for growing food. Individual rooms could be dug out of the walls of the pit to provide more space and better radiation protection, and there might even be some useful mineral deposits down there too.
The other advantage of exploring caves on Mars? They might have provided a good environment for alien life for the same reasons they'd provide a good environment for human life, and if there are any Martians left, a cave is a good place to start looking for them.